AlloDerm implants for prevention of Frey syndrome after parotidectomy: a systematic review and meta-analysis

Evaluation of functional and aesthetic outcomes of free dermal fat graft versus superficial musculoaponeurotic system flap after superficial parotidectomy: randomized clinical trial

BACKGROUND

Parotidectomy is the standard procedure for treatment of many parotid lesions; however, it has several drawbacks. Facial asymmetry and Frey's syndrome are the most annoying complications to patients. Insertion of interpositioning grafts into the parotidectomy bed can decrease these complications significantly. Free dermal fat graft (FDFG) and superficial musculoaponeurotic system (SMAS) flap have very promising results. This RCT aimed to compare these two techniques regarding functional and aesthetic outcomes.

METHODS

Between February 2016 and October 2021, adult patients undergoing superficial conservative parotidectomy in a single centre for a benign indication were randomized into two equal groups using a closed envelope method. In one group, FDFG was inserted at the parotidectomy bed, whereas, in the other group, SMAS flap was performed. Preoperative, operative, and postoperative data were recorded and analysed. The primary outcome was the development of Frey's syndrome.

RESULTS

Seventy-eight patients were randomized into two equal groups of 39 patients. There was no significant difference between the two groups regarding development of Frey's syndrome. There was no significant statistical difference between study groups regarding demographic data, co-morbidities, parotid pathologies, specimen volumes, total operating time, and postoperative complications. A tendency for over correction was observed in FDFG and under correction in SMAS flap. There was no statistically significant difference between the study groups regarding the patients' aesthetic satisfaction with the majority displaying excellent satisfaction with no poor results.

CONCLUSION

FDFG and SMAS flap are simple, rapid, and reliable procedures and are effective in improving both functional and aesthetic outcomes post-parotidectomy. They have comparable results; however, selection of either procedure can be determined according to patient and tumour characteristics. Registration number: NCT05452837 (http://www.clinicaltrials.gov).

Macrophage response mediated by extracellular matrix: recent progress

Biomaterials are one of efficient treatment options for tissue defects in regenerative medicine. Compared to synthetic materials which tend to induce chronic inflammatory response and fibrous capsule, extracellular matrix (ECM) scaffold materials composed of biopolymers are thought to be capable of inducing a pro-regenerative immune microenvironment and facilitate wound healing. Immune cells are the first line of response to implanted biomaterials. In particular, macrophages greatly affect cell behavior and the ultimate treatment outcome based on multiple cell phenotypes with various functions. The macrophage polarization status is considered as a general reflection of the characteristics of the immune microenvironment. Since numerous reports has emphasized the limitation of classical M1/M2 nomenclature, high-resolution techniques such as single-cell sequencing has been applied to recognize distinct macrophage phenotypes involved in host responses to biomaterials. After reviewing latest literatures that explored the immune microenvironment mediated by ECM scaffolds, this paper describe the behaviors of highly heterogeneous and plastic macrophages subpopulations which affect the tissue regeneration. The mechanisms by which ECM scaffolds interact with macrophages are also discussed from the perspectives of the ECM ultrastructure along with the nucleic acid, protein, and proteoglycan compositions, in order to provide targets for potential therapeutic modulation in regenerative medicine.

Comparison of the use of allogenic acellular dermal matrix on rates of Frey syndrome post parotidectomy: A systematic review and meta-analysis

OBJECTIVE

The aim of this study was to evaluate the efficacy of acellular dermal matrix (ADM) use in reducing Frey syndrome (FS) rates in patients postparotidectomy.

STUDY DESIGN

We performed a systematic review and meta-analysis of existing literature comparing rates of FS with and without ADM use.

RESULTS

Eight studies were shortlisted for qualitative study, of which 7 compared rates of FS with and without the use of ADM. A total of 211 patients underwent parotidectomy with the use of ADM. Of these, mean patient age was 44.7 (SD ± 7.2); 89 of 159 were pleomorphic adenoma (55.9%), 29 of 159 with histological diagoses stated were Warthin's tumor (18.2%), and 159 of 211 were other histologic diagnoses (25.7%). Subjective and objective incidence rates for FS were 23 of 211 (10.9%) and 7 of 211 (3.3%), respectively. Patients in whom ADM barriers were used had significantly lower rates of subjective and objective FS (relative risk = 0.22; 95% confidence interval, 0.09-0.57; P = .002; and relative risk = 0.07; 95% confidence interval, 0.07-0.33; P < .001), respectively, compared to patients with no ADM.

CONCLUSION

The use of ADM was associated with lower FS rates compared to no ADM and should be considered in routine use to prevent this condition.

Soft Tissue Reconstruction of Parotidectomy Defect

This article provides a review of soft tissue reconstructive options for the parotidectomy defect, including skin incision, primary closure, acellular dermis, autologous fat transfer, local and regional flaps, and free tissue transfer. The authors discuss considerations for volume enhancement, skin coverage, prevention of Frey syndrome, tumor surveillance, and potential complications.

Autologous Free Dermal-Fat-Fascial Graft for Parotidectomy Defects: A Case Series

Background:

Frey’s syndrome and facial asymmetry from loss of parotid tissue are long-term sequelae of parotid surgeries causing significant morbidity. Various techniques have been used to fill the parotidectomy defect, preserve facial contour symmetry, and prevent Frey’s syndrome. Free dermal-fat-fascial graft (DFFG) is one such technique; however, its use is largely undocumented in the literature. In this case series, we investigate the efficacy of free DFFG in reconstructing parotidectomy defects at 2 tertiary care centers.

Materials and methods:

Medical records of 54 patients who underwent primary parotidectomy and immediate reconstruction with autologous abdominal free DFFG by 2 surgeons in George Washington University Hospital and McGill University Health Centre between 2007 and 2019 were collected prospectively. Patients responded to 2 questionnaires addressing postoperative outcomes.

Results:

Fifty-four patients were included; 32 superficial parotidectomies and 22 total parotidectomies were performed for 39 benign and 15 malignant tumors. Thirty-seven patients could be reached. Out of 37 patients who responded to the first questionnaire, 59% (22) reported complete facial symmetry, 27% (10) reported mild hollowness, and 14% (5) reported mild fullness. None declared noticeable hollowness or fullness. While 81% (30) did not experience Frey’s syndrome, 5.4% (2) experienced mild symptoms without disability, and 13.5% (5) experienced debilitating symptoms. Out of 37 patients, 8 patients responded to a second questionnaire addressing the outcome of the abdominal graft donor site. In regard to the donor site, 87.5% (7) were satisfied or very satisfied from its cosmetic appearance, 75% (6) were not bothered by its cosmetic appearance, and 87.5% (7) had no discomfort at the graft donor site. Patients did not report any other symptom at the graft donor site.

Conclusion:

In this large series of total parotidectomies including malignant pathologies, autologous abdominal free DFFG effectively prevented Frey’s syndrome and preserved facial cosmesis in most patients.

Acellular dermal matrix for prevention of Frey's syndrome after superficial parotidectomy of benign tumors

PURPOSE

To evaluate: 1) the efficacy of acellular dermal matrix (ADM) to prevent Frey's syndrome (FS) after superficial parotidectomy of benign tumors. 2) the effect of different follow-up intervals on the incidence of FS.

METHODS

Fifty-five patients with benign parotid gland tumors underwent superficial parotidectomy were divided into two groups: Non-ADM group (n = 31, 56.3%) and ADM group (n = 24, 43.6%). The primary outcomes measure was the incidence of FS. The secondary outcomes were surgical site depression, infection, salivary sialocele, and salivary fistula. Subjective FS was evaluated using a clinical questionnaire submitted via WeChat at 3, 6, 12, 18, 24, and 32 months postoperatively. Objective FS was evaluated using Minor starch-iodine test at 6 and 12 months postoperatively.

RESULTS

There was a statistically significant difference in the incidence of subjective and objective FS when ADM compared with Non-ADM groups (P<0.05). The respective incidence of subjective FS at 3, 6, 12, 18, 24, and 32 months was 4.2%, 8.3%,20.8%, 20.8%, 20.8%, 20.8% in ADM group and 3.2%, 9.7%, 29%, 38.7%, 45.2% in Non-ADM group. The incidence of objective FS after 6 and 12 months was 4.2%, 8.3% in ADM group and 8.3% (2/24), 38.7% (12/31) in Non-ADM group respectively. Five patients in ADM group and 1 patient in Non-ADM group developed sialocele, and all patients resolved with conservative management. Surgical site depression was significantly higher in the Non-ADM group (15/31) compared with (5/24) in ADM (P=0.049). No cases of immune rejection, infection, hematoma, or salivary fistula were observed in ADM group.

CONCLUSIONS

The current study demonstrated that 1) ADM could reduce the incidence of FS in the patients undergoing superficial parotidectomy. 2) the peak onset of about 18 months appear to be acceptable follow-up for the development of FS.

What is the best method for prevention of postparotidectomy Frey syndrome? Network meta-analysis

BACKGROUND

Prevention of Frey syndrome (FS) after parotidectomy using an interposition barrier has long been gaining a wide popularity; however, there is no clear evidence regarding which preventive technique is more effective. The aim of this network meta-analysis (NMA) is to answer the question: What is the best method for prevention of FS after parotidectomy?

METHODS

A comprehensive search of the PubMed, Embase, SCOPUS, and Cochrane library was conducted to identify the eligible studies. The outcome was the incidence of subjective Frey syndrome (SFS) and objective Frey syndrome (OFS). The Bayesian NMA accompanied with a random effects model and 95% credible intervals (CrIs) were calculated using GeMTC R package.

RESULTS

Thirty-four studies (n = 2987 patients) with five interventions, namely Alloderm (ADM), temporoparietal fascia (TPF), sternocleidomastoid muscle (SCM), superficial musculoaponeurotic system (SMAS), and free fat graft (FFG), were compared together and with no interposition barrier (NB). The results of NMA showed a statistically significant reduction in both SFS and OFS when ADM, TPF, SMAS, FFG, and SCM were compared with NB. No statistical differences were observed when comparing ADM, SCM, SMAS, FFG, and TPF. TPF ranked the best of all treatments (59.4%) and was associated with the least incidence of SFS; whereas ADM ranked the best of all treatments (61.1%) and was associated with the least incidence of OFS.

CONCLUSIONS

All interventions (TPF flap, ADM, FFG, SMAS, and SCM) were associated with a significant reduction in the incidence of FS when compared with NB. TPF and ADM showed the best outcome with the least incidence of SFS and OFS, respectively.

Controversies in the Workup and Surgical Management of Parotid Neoplasms

OBJECTIVE

Parotid neoplasms are a rare heterogeneous group of tumors with varied clinical presentation and behavior. Here we provide an evidence-based review of the contemporary approach to evaluation and surgical management of parotid tumors.

DATA SOURCE

PubMed and Web of Science Databases.

REVIEW METHODS

Searches of the PubMed and Web of Science databases were performed on subjects related to the diagnosis and surgical management of parotid neoplasms. Particular emphasis was placed on the following areas: evaluation of parotid tumors, including imaging workup and the utility of fine-needle aspiration; extent of surgery of the primary lesion, including the extent of parotidectomy as well as oncologic management of the facial nerve; the extent of surgery of involved and at-risk cervical lymphatics; and parotid bed reconstruction. Articles published from 2014 to the present were prioritized, supplementing with information from prior studies in areas where data are lacking.

CONCLUSION

A summary of the literature in these areas is outlined to provide an evidence-based approach to evaluation and management of parotid neoplasms.

IMPLICATIONS FOR PRACTICE

While data are available to help guide many aspects of workup and management of parotid neoplasms, further research is needed to refine protocols for this heterogeneous group of diseases.

Graft interposition for preventing Frey's syndrome in patients undergoing parotidectomy

BACKGROUND

Frey's syndrome is characterised by transient flushing and sometimes facial sweating in the area of the auriculotemporal nerve. It most commonly occurs after parotidectomy, but other causes may include submandibular gland surgery, mandibular condylar fracture, obstetric (forceps) trauma, sympathectomy and metabolic disease. Although the pathophysiology of Frey's syndrome remains controversial, the generally accepted hypothesis is that it occurs as the result of injury to the auriculotemporal nerve.There is currently no clear evidence to establish the efficacy and safety of the different methods used for the treatment of Frey's syndrome, therefore the prevention of this symptom during surgery is important. The main method used for prevention is the interposition of a graft between the skin flap and the parotid bed during surgery. Biomaterials, allograft or autograft can be used for this purpose.

OBJECTIVES

To evaluate the effects and safety of biomaterial, allograft or autograft interposition for the prevention of Frey's syndrome in patients undergoing parotidectomy, and to identify its effect on prevention and delayed occurrence.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Trials Register; Cochrane Register of Controlled Trials (CENTRAL; 2019, Issue 2); Ovid MEDLINE; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 5 February 2019.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in patients with parotid disease (including tumours, inflammation, trauma etc.) undergoing parotidectomy with a minimal follow-up period of six months. We planned to include trials with interventions including biomaterial, allograft or autograft interposition alone or in combination with other surgical techniques. We included trials that compared any graft interposition and no graft interposition, or different graft interpositions.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Our primary outcome measures were incidence rate of Frey's syndrome assessed clinically (Minor's starch-iodine test) and other complications (postoperative infection, subjective painful or restricted cervical movement, scar spread, rejection of the graft, complications related to the donor site such as accessory nerve injury and haematoma). Our secondary outcome measures were incidence rate of Frey's syndrome assessed by participants (by questionnaire) and sweating area assessed by Minor's starch-iodine test. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

We included three RCTs (124 participants), two of which we assessed as at high risk of bias and one at unclear risk of bias. All studies were hospital-based and recruited participants undergoing superficial parotidectomy. Most participants were diagnosed with benign lesions of the parotid gland. Participants were followed up for more than six months. The studies evaluated the two comparisons shown below:Sternocleidomastoid muscle flap versus no flapTwo studies assessed this comparison. Both assessed the effects of the sternocleidomastoid muscle flap procedure on the incidence rate of Frey's syndrome assessed clinically but neither showed a significant difference between groups (risk ratio (RR) 0.08, 95% confidence interval (CI) 0.00 to 1.23; 24 participants and RR 1.23, 95% CI 0.88 to 1.73; 36 participants; very low-certainty evidence). We did not pool the data due to the high heterogeneity (I² = 87%).One study found that the sternocleidomastoid muscle flap may result in little or no difference in other complications including haematoma (RR 2.18, 95% CI 0.09 to 50.16; 36 participants; low-certainty evidence), subjective painful or restricted cervical movement (RR 0.54, 95% CI 0.14 to 2.05; 36 participants; low-certainty evidence) and scar spread in the cervical region (RR 0.71, 95% CI 0.05 to 10.54; 36 participants; low-certainty evidence). Both studies reported the incidence rate of Frey's syndrome assessed by participants, with one reporting no events in either group and the other finding no evidence of a difference (RR 0.63, 95% CI 0.32 to 1.26; 36 participants; low-certainty evidence).Acellular dermal matrix versus no graftOnly one study assessed this comparison. Use of an acellular dermal matrix graft may result in little or no difference to the incidence rate of Frey's syndrome (assessed clinically) in comparison with the no graft group, but the evidence is very uncertain (RR 0.08, 95% CI 0.00 to 1.25; 30 participants; very low-certainty evidence).Acellular dermal matrix may slightly increase the wound infection rate compared with control (RR 17.00, 95% CI 1.02 to 282.67; 64 participants; low-certainty evidence). Acellular dermal matrix may result in little or no difference to the incidence of seromas or sialoceles (RR 2.33, 95% CI 0.66 to 8.23; 64 participants; low-certainty evidence). Acellular dermal matrix may result in little or no difference to the incidence rate of Frey's syndrome (assessed by participants) in comparison with the no graft group (RR 0.33, 95% CI 0.04 to 3.04; 64 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

The evidence for the effectiveness of graft interposition in preventing Frey's syndrome is of low or very low certainty. The use of acellular dermal matrix may be associated with an increase in the wound infection rate, and little or no difference in the incidence of seromas or sialoceles. Further studies are needed to draw reliable conclusions.

Transthoracic Pulmonary Artery Denervation for Pulmonary Arterial Hypertension

Objective—

Pulmonary arterial hypertension is characterized by progressive pulmonary vascular remodeling and persistently elevated mean pulmonary artery pressures and pulmonary vascular resistance. We aimed to investigate whether transthoracic pulmonary artery denervation (TPADN) attenuated pulmonary artery (PA) remodeling, improved right ventricular (RV) function, and affected underlying mechanisms. We also explored the distributions of sympathetic nerves (SNs) around human PAs for clinical translation.

Approach and Results—

We identified numerous SNs in adipose and connective tissues around the main PA trunks and bifurcations in male Sprague Dawley rats, which were verified in samples from human heart transplant patients. Pulmonary arterial hypertensive rats were randomized into TPADN and sham groups. In the TPADN group, SNs around the PA trunk and bifurcation were completely and accurately removed under direct visualization. The sham group underwent thoracotomy. Hemodynamics, RV function, and pathological changes in PA and RV tissues were measured via right heart catheterization, cardiac magnetic resonance imaging, and pathological staining, respectively. Compared with the sham group, the TPADN group had lower mean pulmonary arterial pressures, less PA and RV remodeling, and improved RV function. Furthermore, TPADN inhibited neurohormonal overactivation of the sympathetic nervous system and renin-angiotensin-aldosterone system and regulated abnormal expressions and signaling of neurohormone receptors in local tissues.

Conclusions—

There are numerous SNs around the rat and human main PA trunks and bifurcations. TPADN completely and accurately removed the main SNs around PAs and attenuated pulmonary arterial hypertensive progression by inhibiting excessive activation of the sympathetic nervous system and renin-angiotensin-aldosterone system neurohormone-receptor axes.

Diagnostic significance of circulating multiple miRNAs in breast cancer: a systematic review and meta-analysis

Aims: To determine whether circulating multiple miRNAs can be used as novel biomarkers for the diagnosis in breast cancer, we performed a systematic review and meta-analysis. Materials & methods: After searching the databases of PubMed, EMBASE and Web of Science, we used the bivariate meta-analysis model to summarize the diagnostic indices and plot the summary receiver operator characteristic curve. Results: The summary estimates revealed that the pooled sensitivity was 88% (95% CI: 82–93%); specificity was 84% (95% CI: 74–91%); positive likelihood ratio was 4.69 (95% CI: 2.93–7.51); negative likelihood ratio was 0.15 (95% CI: 0.09–0.25); diagnostic odds ratio was 38.21 (95% CI: 13.41–108.85); and the area under the curve was 0.93 (95% CI: 0.90–0.95). Conclusion: These results suggested that circulating multiple miRNAs might serve as novel biomarkers for breast cancer, with a relatively high level of accuracy.

Blood-based multiple-microRNA assay displays a better diagnostic performance than single-microRNA assay in the diagnosis of breast tumor

Accumulating evidence has suggested that concentrations of blood-based circulating micro-ribonucleic acids (microRNAs, miRNAs) in breast tumor patients are significantly higher/lower than that in normal individuals, indicating that circulating miRNAs may serve as novel blood-based biomarkers for breast tumor. However, the results of previous studies on this issue have been inconclusive. Therefore, we perform a meta-analysis to determine whether aberrant miRNA expression can be used as molecular markers in blood for the diagnosis of breast tumor. PubMed and other databases were searched to identify eligible studies. The sensitivity and specificity were used to plot the summary receiver operator characteristic curve and calculate the area under the curve (AUC). Finally, 15 articles with a total of 1,428 breast tumor patients and 952 healthy individuals were involved. The summary estimates revealed that the pooled sensitivity was 76 % with 95 % confidence interval (CI) of 67-83 %; the specificity was 87 % with 95 % CI of 77-93 %; the PLR was 5.9 with 95 % CI of 3.3-10.4; the NLR was 0.28 with 95 % CI of 0.20-0.39; the DOR was 21 with 95 % CI of 10-44; and the AUC was 0.88 with 95 % CI of 0.84-0.90. The most noteworthy is that multiple-miRNA assay displayed a better diagnostic performance than single-miRNA assay. In summary, the results of the present meta-analysis suggested that blood-based miRNAs may serve as novel molecular biomarkers for breast tumor, with a relative high level of accuracy, especially based on multiple-miRNA assay. Further large-scale prospective studies are necessary to validate their potential applicability for breast tumor prognosis, treatment, and surveillance.

P2X(7) receptors in cerebral ischemia

Cerebral ischemia is one of the most common diseases resulting in death and disability in aged people. It leads immediately to rapid energy failure, ATP depletion, and ionic imbalance, which increase extracellular ATP levels and accordingly activate P2X7 receptors. These receptors are ATP-gated cation channels and widely distributed in nerve cells, especially in the immunocompetent cells of the brain. Currently, interest in the roles of P2X7 receptors in ischemic brain injury is growing. In this review, we discuss recent research progress on the actions of P2X7 receptors, their possible mechanisms in cerebral ischemia, and the potential therapeutic value of P2X7 receptor antagonists which may provide a new target both for clinical and for research purposes.

The sternocleidomastoid muscle flap for the prevention of Frey syndrome and cosmetic deformity following parotidectomy: A systematic review and meta-analysis

Approximately 34-86% of neoplasms of the salivary glands are located in the parotid gland and parotidectomy is the first-line treatment for parotid gland tumors. Frey syndrome and cosmetic deformity are common complications experienced by patients following parotidectomy and the sternocleidomastoid muscle flap (SCMF) is used to prevent them. Numerous studies have been performed to examine the effectiveness of the SCMF for the prevention of cosmetic deformity and Frey syndrome, however, they provide contradictory results and possess small sample sizes with consequently low statistical power. In order to evaluate the effectiveness of the SCMF for the prevention of Frey syndrome and cosmetic deformity following parotidectomy, we performed a systematic review and meta-analysis based on published randomized controlled trials (RCTs), which were identified using PubMed and CNKI databases, and references of studies up to August 2012 were included. Using these criteria, we yielded 11 RCTs. Following an independent assessment of the methodological quality of these studies and the extraction of data, a systematic review and meta-analysis was conducted. The results of the meta-analysis demonstrated that there was a significant trend towards a lower risk of objective incidence [67%; risk ratio (RR), 0.33; 95% confidence interval (CI), 0.16-0.67; P<0.01] and subjective incidence (66%; RR, 0.34; 95% CI, 0.16-0.75; P= 0.01) of Frey syndrome in the SCMF group. The sensitivity analysis also indicated that this result was significant. Due to the considerable variation between the included studies, a meta-analysis was not applicable to assess cosmetic deformity. Two RCTs demonstrated that the difference between the SCMF and no SCMF group was not statistically significant, while the other seven RCTs detected a statistically significant difference between the two groups. Publication bias was detected. In conclusion, based on currently available evidence, the use of the SCMF is benefical for the prevention of Frey syndrome, however, whether it is also benefical for cosmetic deformity remains inconclusive.